What were Zygalski sheets in WWII cryptography?

Zygalski sheets were a cryptologic technique invented around October 1938 by Polish mathematician and cryptologist Henryk Zygalski. Used by the Polish Cipher Bureau and later by British cryptologists at Bletchley Park, these sheets helped make the decryption of German Enigma machine messages more efficient before and during World War II.

What we know

• The method of Zygalski sheets was a cryptologic technique used to decrypt messages enciphered on German Enigma machines. [2]
• The technique takes its name from Polish Cipher Bureau mathematician and cryptologist Henryk Zygalski. [2, 3]
• Henryk Zygalski devised his sheets around October 1938 to make Enigma cipher-breaking more efficient. [2, 4]
• The technique was utilized before and during World War II by the Polish Cipher Bureau, and subsequently by British cryptologists at Bletchley Park. [2]

Where to go next

• whoWho was Henryk Zygalski?
• how it workedHow did the Enigma machine work?
• the bigger pictureWhat was the Polish Cipher Bureau?
• whereWhat happened at Bletchley Park during World War II?
• what caused itHow did Marian Rejewski break the Enigma cipher?
• an unexpected connectionHow did French intelligence assist early Enigma decryption?The successful early mathematical breaking of the Enigma cipher by Marian Rejewski relied not only on group theory, but also on secret intelligence material supplied by France originating from a German spy.

Sources

• [1]Zygalski sheets (Wikidata Q2185271) · CC0 1.0
• [2]Zygalski sheets · CC BY-SA 4.0
• [3]Henryk Zygalski · CC BY-SA 4.0
• [4]Cryptanalysis of the Enigma · CC BY-SA 4.0
• [5]Enigma machine · CC BY-SA 4.0